package com.helloworld.demo;

public class ThreeColorRemark {
    public static void main(String[] args) {
        Aa aa = new Aa();

        Dd dd = aa.bb.dd;
        aa.bb.dd = null;
        aa.dd = dd;
    }
}

class Aa{
    Bb bb = new Bb();
    Dd dd = null;
}

class Bb{
    Cc cc = new Cc();
    Dd dd = new Dd();
}

class Cc{

}

class Dd{

}
